The Surgeon
by BlueNeutrino
Summary: Sequel to The Physician. Dean takes Carter up on her offer of surgery to fix the damage done by Metatron, but even with Sam and Cas' support, it's not going to be smooth sailing... Season 10, canon divergence, MOC-themed.
1. I

**A/N: So...there was a good response to the original fic both here and on AO3. I had a few requests for a sequel. I really enjoyed writing it and people seemed to enjoy reading it, so I saw no reason to stop. Cross posting this here from AO3.  
**

 **Customary disclaimer: This is written for fun, not for profit. I claim no ownership of the recognisable characters.**

 _"Hello?"_

 _"Dr Carter? It's…"_

 _"Winchester. Yeah, I thought you might call. You run out of meds?"_

 _"No. Well, yeah, but that's not why I'm calling."_

 _"Oh?"_

 _"Yeah, um…you remember that surgery you mentioned?"_

Dean had never wanted to make that phonecall. He hadn't wanted to make it with Sam standing there, anger and fear and desperation painted plain on his face. He hadn't wanted to make it with Cas solemnly listening in, hearing Dean finally admit just how bad things had gotten and that he needed help.

 _"You said you weren't going to have surgery."_

 _"I…I changed my mind."_

 _"What happened?"_

He didn't want to tell her what happened. He didn't even know how. _I almost killed an innocent person and when my brother stopped me my heart was pounding so hard I thought it was going to give out._ It was hard enough to even admit to himself. Harder still to say out loud with Sam standing there.

 _"I, uh…I…"_

Carter took pity on him before he even had chance to try and answer. _"Know what? It doesn't matter. But you're sure you want the surgery?"_

 _"Yes."_

 _"Alright. I can do that. Just give me a week to get all the stuff together."_

 _"So, you want me to come up to Chicago next Tuesday?"_

 _"No. I'm not there anymore. I move around a lot. I'll text you the new address."_

And that was how he'd ended up in an underground parking garage in Denver, knocking at the door to a basement apartment and hoping he was in the right place. Sam and Cas hovered apprehensively a few paces behind.

Several seconds pass in silence before Dean raps anxiously on the door again, but all it earns him is a glare for his impatience as the door swings open a heartbeat later. Carter gives him a cold look, not even greeting him as she casts a glance over his shoulder. "Who are they?"

"Oh, uh… that's my brother, Sam. And Cas. He's my friend."

"Hmm." She narrows her eyes. "They can wait out here." She gives a sharp jerk of her head to invite him in, but Sam protests before Dean even has chance.

"We're coming inside." His tone is firm. Almost intimidating, if Carter didn't just respond with a derisive smirk.

"This isn't a hospital. I don't have a relatives' room. There's a 24 hour café down the street, if you want somewhere to wait." She seems impatient to get Dean inside, holding the door open and shooting him a glare, but he stands stoically where he is.

"I'm having major surgery, here. You told me I wouldn't be able to drive for at least a month."

"I meant have someone pick you up in a week." Her face is still scowling in annoyance, but she seems to realise he's not about to come in unless Sam and Cas do too.

"Are you fucking serious?"

They both exchange a glare for a few seconds, but then Carter rolls her eyes. "Alright, fine. They can come in for the pre-op stuff, but I want them out after."

For now, Dean will take that. He hoists his duffel bag onto his shoulder and steps inside, Sam and Cas close behind. Carter's wearing a black tank top this time, the puncture marks on the inside of her arm still noticeable, although there's no angry bruise. Still, Dean's sure Cas and Sam must have noticed, and it makes him nervous. He's also noticing for the first time the blotchy ring of white, uneven scar tissue around her upper arm, like a burn, and it's raising even more questions.

Sam and Cas cast a suspicious glance around the new apartment at the same time as Dean. It's no cozier than Chicago; if anything even gloomier due to the lack of windows, and the walls are all granite blocks painted in faded-looking black gloss. The floor comprises black and white vinyl tiles that seem to have barely survived from the 80s. There are at least actual walls with doors this time, but the first area the entrance leads into is rather small combined kitchen and living space.

Carter waves in the direction of a couple of battered leather sofas for them to sit. Cas instead chooses to stand, arms crossed haughtily as he narrows his eyes at Carter. "So you're the demon doctor?"

"Yeah. And who are you? His accountant?"

"I'm an Angel of the Lord."

She just sneers. "That would be a little more impressive, were I Christian. Now you gonna sit, or not?"

Cas still hesitates, but with a look from Dean, perches himself awkwardly on one of the couches beside Sam. Carter sits herself down comfortably opposite Dean, reaching for the folder she's left lying on the coffee table between them. "Alright, so… I didn't send you any pre-op literature, but there's some generic stuff there I swiped from the hospital if you're interested. I got your bed prepped. How long of a stay did you pack for?"

"Just a week, like you suggested. Is that still okay?"

"For _you,_ yeah." He notices she's not looking at either Sam or Cas. "I need to do a pre-op assessment before we go any further. I've got the room set up that way, if you want to come through?"

Dean glances round nervously, again taken aback by how quickly things are moving. Cas and Sam are both still looking apprehensive. "Why don't you tell us more about what you're going to do to him first?" Sam demands of her, but she just shrugs.

"You're not my patients. If Dean wants you to know, he can tell you."

"Look…" Dean can see the situation elevating quickly if he doesn't say something. He doesn't know why she's being so damn hostile. "I want them here. They're family. Can't you at least let them see what's going on?"

For a moment she purses her lips, turning her glare on him, but then just sighs as she decides it isn't worth it. "Alright. _Fine._ You all coming through, then?"

It seems to take Sam and Cas by surprise too, but there's no further protest as she leads them into the room set up for surgery. Dean dumps his stuff down by the sofas and follows.

As they enter, Dean recognises the familiar black vinyl exam table taking pride of place in the center of the room, and some of the other equipment also appears to have made its way here from Chicago. There's definitely a few machines and instruments he hasn't seen before.

"A power drill?" he hears Sam remark, his tone the exact mix or horror and apprehension that it's just triggered in Dean, and he's glad he didn't spot the device first.

Carter just gives a huff, not even glancing in his direction. "It's for trepanning. I work with what I have."

"Trepanning?"

"You fit it to a device on someone's head so you can drill a hole just far enough to…" She trails off, looking annoyed. "Why I am I even explaining this to you? It's not relevant."

Sam doesn't seem keen to pursue the question as she goes to retrieve a cart stacked with monitors and equipment, waving in the general direction of the table. "You know the drill."

Dean does, but he's quickly realising having Sam and Cas here does actually feel somewhat awkward. He strips off his jacket and shirt and then sits down as he waits for her to cross back over. He notices Sam is watching Carter suspiciously, while Cas is more concerned with watching him.

"You two can stand there like lemons, or you can…actually, I don't know what the fuck you can do," she shoots at the pair of them as she snaps on a pair of gloves and slings a stethoscope around her neck. She turns her back on them both as her attention turns to Dean. "Alright, I just need to see how things have progressed since last time. Shouldn't take long."

She starts with his blood pressure, working efficiently as she fastens the cuff around his bicep and inflates it. The only indication of the results is her slight scowl as she unwraps it again. "I'd ask if you watch your cholesterol, but somehow I don't think that's the root of the problem."

He bites his lip. "Not good?"

"I doubt you'd be here if it was."

Most of the tests from last time get skipped as she moves straight to pressing the stethoscope to his chest. His hisses from the cold, wishing she'd offer to turn the heating up again, but she does no such thing.

"Yeah, that definitely sounds worse," she remarks after a few moments listening, moving the diaphragm around to different spots on his chest. Hardly the most encouraging thing to hear.

"Don't sugar coat it," he retorts, but she just shrugs.

"That _was_ sugar coated. The murmur's got really harsh and your resting rate's in triple figures. Definite irregularities, too. I need to get a closer look." She turns back to the equipment tray, and he keeps his eyes locked on her hands as she fills up a syringe. He knows what's coming.

There's a somewhat condescending, almost mocking fake smile on her face when she turns back to him. "Now this is some contrast agent. I need to inject it so I can see your heart better on the ultrasound. Don't lose your shit or anything."

He clenches his jaw wordlessly, knowing he earned that, but Sam interrupts as she starts slapping his arm to help find a vein. "What are you giving him?"

She doesn't even glance back over her shoulder at him. "Contrast agent, L'Oréal. Your ears not work?"

"What's in the contrast agent?"

Only Dean sees the roll of her eyes. "It's agitated saline. Completely harmless, I promise. Hospitals use it all the time." Then she plunges the needle into a vein.

Dean grimaces, but he wasn't unprepared as the needle slides out again. "Alright. Lie down," she instructs, although Dean can still see Sam watching cautiously over her shoulder. He does as he's told, trying to get comfortable as she brings the ultrasound machine closer. The screen flickers to life when she hits the power, although its display remains blank. "This is probably gonna feel cold…" That's the only warning he gets when she starts smearing the ultrasound gel on his chest and positions the wand. His sharp intake of breath belies that yes, it's cold. Like she's been storing it in the fridge.

Grainy images flicker across the screen and he hears the rapid _whoosh-whoosh_ of his heartbeat, something he'd only half expected from the limited medical knowledge he's gained from _Dr Sexy, MD._ He has some idea of how the device is supposed to work, but most of the quivering shapes on the display are meaningless to him. Instead, he watches Carter's face. Despite her usually perfect look of apathy, even she's struggling to keep her expression blank. "Yeah, that's…" He doesn't like the way she's biting her lip. "That valve's completely fucked." The wand slides lower, closer to his sternum. "And the right side of your heart is just…not doing what it's supposed to. At all." She doesn't point out anything specific, but he can see the rapidity with which the on-screen shapes are fluttering. "Honestly, I don't even know how it's beating like that and you still managed to walk in here upright." She slides the wand right again, and down, scrutinising the display for a few more moments. "Right. That scar tissue there has to go." Her hand waves vaguely over the bottom left of the screen, but Dean thinks he can see the cluster of white she's referring to. His mouth goes dry and he swallows nervously. On the screen, he thinks he sees the disruption to the pulsating rhythm as his heart gives a skip.

"Right…" She removes the wand from his skin and straightens up, throwing a few tissues at him to clean away the gel. He scowls slightly, but starts trying to wipe the jello-ish substance off his chest. Meanwhile, Carter at last turns her attention to Sam and Cas with a cold glare. "Based on that, I'm happy to proceed with the surgery immediately. But you two need to go."


	2. II

Cas doesn't exactly look co-operative, but Sam's expression is downright hostile. "We aren't going anywhere."

Carter takes a couple of paces closer to him, her eyes narrowing. "You want your brother to get the treatment he needs or not? I need you out of my way."

"If you expect me to just stand around waiting while you crack open my brother's chest and start carving into his heart, I'm going to need more of a reason to trust you first."

A look of indignation crossed with annoyance passes over Carter's face. "Look, sunshine, if I wanted to harm your brother I've had plenty of opportunity, and there's fuck all either of you could do to stop me. I take pride in doing my job well, so you damn well better believe he'll be fine."

The conflict's making Dean anxious. He glances over at Cas, who makes eye contact, gaze calm and reassuring. It helps a little.

"Well, where's your assistance?" Sam continues. "Normally you need a whole team of people to make a surgery successful, yet the only person I see here is you."

"Because _I know what I'm doing_ ," she practically snarls. "You want someone else in the room for surgery? Well how about you show me your diploma from med school. Otherwise, get the fuck out of my way."

"I don't need an MD to know you need more than one person performing major surgery."

Lord knows Dean wants Sam to stay, but he doesn't want this. "Sam…" he chances an interruption, but neither of them seem to hear.

"Well, I don't know what you think you'd be bringing to the table if you just loitered while I…"

As Dean exchanges another pleading look with Cas, the angel finally decides to intervene. It doesn't exactly defuse things, but Dean feels the knot in his stomach unwind just slightly. "I may not have a medical degree, but I do have all of human history's worth of medical knowledge to hand," he offers. "I can assist you, if it would be beneficial to Dean."

His tone is calm, but Carter rounds on him with an expression no less agitated. "Oh, so you're an expert in medicine?" she retorts. "That's just great! Why am I even needed? Why don't you just go heal him yourself? Oh, that's right. You can't."

It's brutal. Moreso than she even realises, and Dean could swear he sees Cas flinch. He knows how useless the angel feels, and how much he loathes it.

"I don't want to antagonise you. I only want what's best for Dean." The angel's self-control is remarkable.

There's a beat, Carter briefly looking like she wants to prolong the argument, but then Dean tries speaking up again. "Doc, please…"

She glances back at him. "You want him here?" It's a sincere question, not a challenge.

"I do."

Another pause, then she sighs and nods. "Alright. Angel Cakes can stay, But you," – she turns back to Sam – "You need to find somewhere to wait. You're too angry and ask too many questions, and I can't trust you not to interfere. I suggest you check out that 24 hour café I mentioned."

Sam grits his teeth, unconvinced, but a glance exchanged with Dean pacifies him. _It's alright. Cas will be here,_ the look seems to say, and finally he lets out a breath as he concedes. "Alright."

Carter gives a nod and then crosses over to one of the tables, picking up a set of keys. "If the pair of you want to be useful, you can go run this errand for me. There's a black van in the parking lot; got a heart-lung machine in the back. It's kinda big and I hadn't figured how to get it down the steps into the apartment compound on my own, if you could go fetch it." She dangles the keys if front of Sam, and he purses his lips briefly before accepting.

" _Fine_ ," he says, glancing back at Dean to check it's okay for them to leave before he and Cas make their way out of the apartment again. Carter returns to prepping for the surgery, not even looking at Dean.

Somewhat awkwardly, he repositions himself back on the side of the table and clears his throat. "I could be wrong, but you seem pissed."

She doesn't even give him a glance. "Not at all."

"Try that again without scowling."

Now that gets a reaction. She rounds on him, full on glare aimed in his direction. "Alright, I'm pissed. I agreed to see you, not anyone else. You didn't even think to mention they'd be coming down with you."

"I didn't realise it would be such a big deal. I mean, why is it? I just want my family here."

She gives a huff, throwing her hands up in the air in frustration and then letting them drop. "You know what? I…I don't even know. It's just not how I'm normally used to doing things." She goes to fetch a folded up piece of material from one of the tables and then crosses back to him. He notices her expression has softened somewhat, although in place of the scowl there's now an almost-smirk. "Actually, I think I just like having you to myself."

"Oh?" He can't help the blush that spread across his cheeks, and she chuckles.

"Go put this on." He glances down at the hospital gown she's holding out to him, and turns even brighter crimson.

"There's a screen over there, if you're gonna get all shy on me." Now that Sam and Cas are gone, she seems positively amused. "I'll start to get things set up."

He accepts the garment without a word and goes to get changed.

It takes a couple of minutes for Dean to emerge from behind the screen again, looking decidedly uncomfortable in the thin hospital gown. Carter doesn't say anything, but she still has that perpetual not-quite-smirk on her face as she invites him to lie back down on the exam-doubling-for-operating table. He shivers slightly as he gets himself in place. The new apartment is still no warmer than the last.

"Nervous?" she asks, wheeling over a cart of monitors as she continues with the surgery prep.

He shoots her a scowl. "Do you really need to ask?"

"Not really. Just curious." She slips the cuff round his arm to monitor his blood pressure, then moves onto the EKG stickers for his chest. "So…does having Angel Cakes and Brother Dearest here really make you feel better?"

"Actually, yeah." It strikes him as a strange question. "Just knowing I'm not alone helps."

"Hmm." She seems sceptical, inexplicably so to him, but she doesn't elaborate. "Alright, needle again," she says as she prepares to insert his IV. "Since I feel obligated to warn you every time now."

He clenches his jaw, but knows he doesn't really have a right to retaliate as it pushes in with a sharp sting. It's hard to tell if she's being deliberately rough with him or not.

"Your heart's racing," she remarks with a glance at the monitor screen. "I'll give you a sedative before we start. It will help if you're more relaxed." She collects a syringe from one of the carts and inserts it into the end of his IV line. "And after this, I'm gonna need to do your catheter."

He frowns. "I thought you just…?" His puzzled look turns to horror as he sees the smirk on her face.

"I wasn't talking about the intravenous one."

"Oh fuck…" he grumbles, letting his head fall back and closing his eyes. "Can't you just let me use your bathroom or something?"

She goes to fetch the kit over, switching out her gloves for a fresh pair. "Minimum eight hour surgery, then you're gonna be bedbound for a week. Trust me, you'll be grateful for this." He tries not to think about it as he feels her hands push up the gown and slide between his legs. He's starting to realise why she did well to get Sam and Cas out of the room. "I'm gonna assume you weren't stupid enough to eat anything recently." She continues talking even as she has the tube slid halfway into him, and he grits his teeth.

"Not since last night. Followed your instructions."

"Good." When she's finished, she smooths the gown back over his thighs again and goes to change her gloves. He's still a shade of scarlet by the time she returns. "You comfortable?"

"As I'll ever be."

Satisfied, she glances over at his monitor screen. "The sedative should be kicking in, now. Your heart rate's dropping."

A look towards the monitor tells him it's in the nineties. Not exactly what he'd call steady, but he's not aware of it pounding in his chest anymore. Everything seems strangely calm.

He watches curiously as she continues to set things up, erecting a tripod by the bed and then fixing a camera to it pointing towards his chest. It takes a while for him to finally pass comment. "You gonna explain what that's for, or…?"

"It's for my research." She replies, adjusting the focus on the lens. "I don't get to perform surgery like this often, so it's good to keep a record. That okay with you?"

"If I said no, would it stop you doing it?"

"Nope."

"Oh." He gives her a slightly disgruntled look. "Then I guess I may as well say I'm fine with it, then."

"I appreciate that." She goes back to some trays of equipment, lining up the items she needs and sterilising them one by one. He watches silently for a few more moments, wondering how long it will take Cas and Sam to fetch the bypass machine. He guesses they're having trouble.

"Can I ask you a question?" he says after a couple of minutes.

"You just did."

"Right. Well, I want to ask another one."

"Shoot."

"So…say I'm a demon. My meatsuit gets busted up to the point it doesn't work anymore, so instead of smoking out, why do I come to you?"

There's a beat. It briefly looks like she's debating how to answer, then she says. "Do you have another question?"

That only piques his curiosity further, but he rolls with it. "Do you have a first name?"

Her only response is a mocking laugh. A sardonic look crosses her face as she reverts to his previous question. "Alright. How about this: they come to me for upgrades."

"Upgrades?"

"I told you: I research the applications of alchemy in medicine. I can usually achieve a little more than just restoring basic functionality. Like if you took your crappy 2001 Dell to an IT shop for repairs and walked away with an i7 and 12GB of RAM upgrades."

"So why is it that you only deal with dead meatsuits, then?"

"Because I won't do the procedures if there's somebody else in the body."

That surprised him. He didn't exactly have her down for the moral type. "That what you tell people?"

"Yeah. I've turned demons away for it before."

"What's to stop them just going away and…" It galls him to say it, but now he's opened up the can of worms, he has to ask. "Killing the vessel themselves and coming back?"

She doesn't turn to look at him, but he notices her suddenly go very still, putting down the pair of forceps and sterile wipe she'd been using to clean it. "I won't pretend it hasn't happened."

Not knowing what to say, Dean falls silent. She doesn't offer any further explanation, but glances over to see the troubled look on his face. "You don't like the way I operate, nobody's making you have the surgery." Her tone is firm, but he wouldn't call it angry.

"No, I just… I wanted to know. I'm sorry I asked."

The next few seconds pass awkwardly. There's something else Dean wants to say, and it's making him nervous. "Carter…" His voice is uncertain when he chances to speak again.

"What?"

"Before they get back…if I die on the table…"

She cuts him off. "You're not going to die."

He swallows nervously. "Just trying to be realistic. _If_ I do…if I come back as a demon again…"

There's something in his voice that seems to grab her attention. She stops what she's doing and walks over to him, her expression unreadable. "Then I'd say it would make you more the type of patient I'm used to treating."

He has no idea what to make of that statement. Instead, he just licks his lips and glances down at the familiar restraints on the side of the table. "I'm just saying, these might be a good idea."

She glances down, deliberating for a moment, and then nods. "Alright. One thing first though…" A hand goes to the string securing the gown around his neck and she pulls it loose, folding the thin fabric down to his waist. "Put your hand on your chest."

There's no point pretending he isn't puzzled, but he humors her. "Okay…"

He brings his left hand to rest over his sternum and she places her own on top of it, holding it in place. "This is the last time you're going to get to feel it like that. Try to remember it. The next time you're going to be able to do this, there's going to be a scar."

Now that she's said it, it's a strange thing to contemplate. He can feel his heart thumping faintly beneath his palm, in a way it won't be beating after this is all over. His fingers trace the skin: still smooth, unbroken. By rights, there should already be a scar. An angel blade has already ripped his flesh apart and punched deep into his heart, yet the only evidence that remains is hidden from view. If the universe worked the way it was supposed to, he shouldn't even be alive.

"I'm no stranger to those," he says quietly.

For a brief second, they share an awkward moment of eye contact, and it's Carter who's first to look away. A few heartbeats pass in silence before she removes her hand and wordlessly begins securing the restraints.

"Would you like me to tell you what's going to happen, or would you prefer not to know?" she asks when she's finished, once again refusing to look at his face.

"Did you ever plan on giving me chance to read the file you brought?"

"No."

"Then I think I'll stick with not knowing."

"Works for me."

She's going to fetch rolls of paper to cover the parts of him not intended for surgery when he at last hears the screech of wheels on tiles in the corridor outside, their axles rattling under the load."Looks like Tweedledum and Tweedledee are back," Carter remarks drily.

Sam and Cas reappear in the room a moment later, wheeling the machine between them. Sam shoots Carter a glare. "You had the van backed up into a corner."

She smirks. "Reduced the chances of it getting broken into though, didn't it? I see you got the machine out in the end." She takes over from Cas wheeling it over beside the bed. Dean notes the strategically placed paper sheets hiding his bound wrists and ankles from their view. That's probably for the best.

"Alright, you can go now," she shoots at Sam, "And you, lose the coat and jacket and put one of these on." She's pulling on a polyester apron as she instructs Cas to do the same. It hardly seems like the most sterile setup, yet Dean's still feeling perfectly calm.

Sam, on the other hand…

"You want me to go drink coffee and eat pancakes while my brother's having open heart surgery?"

"Something like that, yeah."

Sam's eyes narrow. "What's with the camera?"

"What do you think? I'm recording." She barks out the reply tersely.

"Why?"

"Why not? How do you think medical advances are made?"

It's not helping the situation, and Sam's look of suspicion and discomfort deepens. "Really? That's what this is about? You do that to all your patients, or are you just getting a kick out of the fact you get to carve up a human for once?"

Carter rounds on him and throws her hands up in exasperation. "See, this is exactly why I don't want you here. You bitch like this during surgery and your brother will be dead within the hour."

It's already growing heated, and Dean doesn't want the fighting to start up again. "Sam, it's okay. Cas will be here. You can come back in a few hours and I'll be just fine."

That doesn't exactly seem to put Sam at ease, but Dean never expected it would. He knows just how distraught he'd be if their positions were reversed. "Alright, just get better okay?" he says, walking over to give Dean a comforting pat on the shoulder before he makes to leave. He shoots Carter one final glare before exchanging a look with Cas. "You take good care of him."

"I will, Sam. I promise."

It seems to be enough to convince Sam to leave, walking back out into the hallway and closing the door behind him. Dean turns to watching the two who remain.

Carter's tying back her hair while Cas has shed the trenchcoat and jacket and is rolling up his sleeves. He shoots her a dubious look at the complete lack of any other hygienic precautions. "Yeah, I know it's not ideal," she says with a roll of her eyes, "But in his case, I really don't think infection's what we have to worry about." There's a sink in the corner of the room which she crosses to to start scrubbing down, and Cas follows her lead.

When she heads back to Dean, wearing a fresh pair of latex gloves and pushing the equipment cart, he sees the tray of perfectly ordered instruments glint beneath the yellow strip lights overhead. Were it not for the sedative, he suspects he'd be feeling a lot more nervous by now.

"Alright, Hot Wings, you good at taking instructions? We need…" Carter cuts off as she sees Cas has already taken the initiative and is bringing over the surgical lamp and the carts of anaesthetic gas and betadine. Dean swears he can see the hint of a smirk.

"Yes, I did think these would be necessary."

Carter pulls a face, then seems to have a change of heart as she instead grins. "Looks like you might be useful after all. Alright, let's get him under."

She takes the lead in connecting the gas tanks to the flowmeter and adjusting the mix, and then brings the mask up to hover in front of Dean's face. "Alright, in ten seconds I'll tell you what my first name is."

Apparently, that seems to be his warning that consciousness will be leaving him very soon. He thinks he can taste the sharp smell of the gas as it floods his mouth and nose, mask pressed securely over his face to seal off the outside air. Fuzziness begins to pervade his awareness, making his body feel light, almost incorporeal while his eyelids simultaneously grow heavy. His instincts are telling him to fight it, yet it's just so _nice_ that he doesn't want to. He doesn't last five seconds.

Carter chuckles softly as she lifts the mask from his unconscious face and prepares to intubate. "I guess you'll never know."


	3. III

**A/N: Medical research was done, but mistakes may remain. Also bearing in mind that Carter is not a conventional doctor, this is not a conventional surgery, and her methods may be unorthodox. At the time of posting, I do not have access to my earlier research materials, so if mistakes are spotted at a later date, they will be amended.**

The pair of them work efficiently, Cas taking instruction readily when needed, but needing very little. They soon have Dean fully prepped, intubation tube down his throat and eyelids taped shut. His chest is exposed, skin yellow with betadine, and Carter runs a final check on the monitors before she picks up a scalpel.

Only once it's hovering just an inch from Dean's chest does she pause. There's a beat, and Cas looks up from Dean to see her watching him. Even for him, it's disconcerting. "What's wrong?"

"You're frowning."

"And this is an issue?"

She lifts the scalpel slightly to point accusatorily at him with the tip. "You want to stay, I need to know you're on board. No reservations."

He glares back. "You're about to slice into the chest of my best friend and operate on his heart. Forgive my expression. I do have concerns."

"Well, lose them." Her face is blank but her eyes hard. "If you're gonna be of any use to me, you need to stop being concerned and do what I tell you without question. Even if you don't want to. Even if it feels wrong. As of now, Dean isn't your friend. He's just a body. An organic machine that needs repairing. And you need to lose your emotional attachment or you're gonna be hesitant, and sloppy, and he's not gonna survive."

Cas clenches his jaw. "Caring about Dean doesn't impede my ability to help him."

"That sounds like you're questioning."

There's a tense pause, then grudgingly, Cas relents. "Alright. I understand."

She seems satisfied. "Good." The scalpel lowers towards Dean's skin again. "I'm making the incision."

She makes quick work of it, one neat slice from just below Dean's collarbone to the bottom of his sternum. Blood gushes out, and she doesn't ask for Cas' help as she reaches for a skin retractor without looking and fits it in. Her movements seem well practiced as she draws back skin and tissues until Cas sees the white of bone. "Alright, you can man suction and packing. I'm getting the saw."

Cas tries to remember what she said about no reservations as he packs gauze beneath the loose layers of flesh and cleans away the blood, but his gaze is drawn to Dean's face. It seems wrong to be doing this to him. Especially…

A sudden buzzing hits his ears as Carter tests the sternal saw. He glances up, anxious, but her expression is serious and professional. "We're good to go. Have I got room?"

She does, but Cas doesn't let his hands stray far as she lowers the saw to Dean's sternum and begins to cut through. The noise is loud, grating, and it sets Cas' teeth on edge.

Again, the cut she makes is neat and straight before she sets the tool aside and reaches for the rib spreader. It slides snuggly into the freshly made crevice, and then she begins to pry the bone apart. Cas sees the yellowish layer of Dean's pericardium emerge below. On either side, pale, spongy lung tissue softly swells and deflates at the ventilator's command.

Once Dean's ribs are spread a rough hand's width apart, Carter holds out an expectant hand. "Scalpel. The big one." Cas hands it to her, and as she lowers it towards Dean's chest, she glances again at his face. "You ever seen a beating heart before?" She seems to be weighing him up.

He gazes steadily back. "I'm an angel. I've _made_ beating hearts before."

"Well, I'm prepared to bet they won't have looked like this." Her expression is unreadable. "I'm just saying, don't let yourself be shocked." Then she begins to slice through the membrane.

As Dean's heart comes into view, Cas understands the warning. The organ looks strangely swollen, misshaped by the ridges of pale scar tissue clinging to the right ventricle. It tries to beat, fast and quivering, yet the entire right side remains stubbornly static, just a slight shudder compared to the frantic pumping of the left. It looks sickly and wrong.

"I told you not to get emotional."

Carter's voice is a rude interruption as Cas gets caught staring, realising he's watching Dean's heart beat. He's focused again in an instant, but she's already pulled across a tube from the heart-lung machine by herself. "This goes in, takes over function, then we stop his heart," she sums up, then too quick for Cas to even register she's pushing a scalpel just beneath Dean's aorta. More blood gushes before Carter jams a tube into the hole she's just made. "Gonna have to do more of these. Help me out."

He assists with the machine, fitting the bypass tubes around Dean's heart until the blood is being adequately diverted. The process isn't straightfoward. There are tubes and stents and cannulas that need fitting, Carter gesturing for each one with an impatient snap of her fingers, but Cas is more than able to keep up. Eventually, they get it so that the machine has completely taken over function of Dean's heart and lungs. Then Carter reaches for a dial by one of the pumps. "Alright, time to stop the ticker. I'm gonna clamp his aorta then start pumping this. Watch the monitors. Heart function needs to drop to minimal." She does as she described, cutting off the blood supply then beginning to let the cold cardioplegic solution flow into the soft tissues of Dean's heart.

Cas watches, anxious yet transfixed, as the regular beating stutters. His eyes should be on the monitor, but he can't help but stare as Dean's heart quivers, jerks, then stills, leaving only minute ripples throughout the tissue. The monitor screeches an alarm.

"Mute that," Carter orders. "We're good."

Cas does. He notices they're smearing blood everywhere, but Carter doesn't seem to care.

"Right-o, then." She picks up a smaller scalpel and a pair of forceps. "That's what's coming off." She jabs the scalpel towards the ridges of scar tissue. "But first I have to go in and fix the valve, if I can. Gonna go through the top of the ventricle, remove some of the harder tissue that's keeping it from closing. You doing okay?"

Her apparent concern for his wellbeing takes him by surprise. "Yes, I'm fine."

"Good. You can stay, then. Fetch me over that stool. This might take a while."

So it wasn't concern. Cas clenches his jaw but does as he's asked.

Carter leaves the angel standing as she gets herself comfortable and leans over Dean's chest, using his shoulder as a prop for her forearms. It makes Cas bristle, but he bites his tongue. "Just keep the blood down and the light focused," she tells him, leaving him in charge of the suction and the lamp. It's not that it isn't essential, but it is menial. Frustration burns in his chest as he watches her work.

She wastes no time in pushing the scalpel straight in, and Cas involuntarily holds his breath as she opens up a hole in the side of Dean's heart. As he clears the fresh rush of blood, Cas can see the near-white of the tricuspid valve flaps. Delicately, Carter pinches one of the leaflets with the forceps and starts scratching at the stiffened tissue surrounding it. It peels away in fine strips, barely wider than a couple of hairs as she's meticulously precise.

There's a lot of blood.

"How exactly did you plan on carrying this out by yourself?" Cas asks as he sucks away more fluid, mildly surprised by how much is pooling in Dean's chest cavity even with the machine pumping for him. Everything he draws through the nozzle gets recycled.

"Dexterity," Carter replies without looking up. "I have two hands. They can multitask."

"You're ambidextrous?"

"No, I'm right handed." If he's being a distraction, she gives no indication of it. "Same as plenty of piano players and guitarists are right handed. Doesn't mean their left hand isn't well trained."

Another, thicker strip of scar tissue peels away from Dean's heart as she begins to carve at the ventricle's outer wall. Cas shuts up and lets her work.

* * *

Sam tried the waffles. Genuinely, he _tried._ Strawberries and cream special, if he's going to be sat here for the next eight hours, but if they were any good, it's lost on him. Everything just tastes bitter. Inevitable when his stomach's churning with anxiety and he can't help but imagine what Dean looks like with his chest cracked open and heart carved to pieces beneath a stranger's knife.

For almost half an hour he pushes the waffles aimlessly around his plate, grimacing when a stab with the fork causes red syrup to ooze between the ridges. He's only managed a few mouthfuls. Sam sighs and pushes the plate to one side. He's not getting his appetite back until he's certain Dean's going to be okay. A waitress comes back over presently, looking slightly concerned as she clears away his barely vacated plate.

"Were the waffles okay for you, sir?"

"Yeah." Sam sighs. "Guess I'm just not hungry."

"Oh. Can I get you anything else?"

"I could go for a coffee. Black." At least that tastes bitter anyway.

She brings it over, giving him a sympathetic look as she pours straight from the cafetiere into his cup, then tries for a smile before she walks away. It only looks awkward.

Sam heaves another sigh then leans back in the uncomfortable plastic seat of the booth. How long has it been? An hour? Two? In whatever case, simultaneously too long and not long enough. He needs to see his brother again, but even more he needs to know the surgery is going well.

It's hard not to let his imagination conjure up the worst as he sips at the coffee, almost grateful that the heat nearly scalds his mouth. He tries to focus on his surroundings: the hardness of cheap plastic at his back; the smell of coffee and grease; the rumble of traffic in the street outside. Voices blend together in a jumbled cacophony of conversations around him, banal phrases slipping into his awareness and out again without ever really registering. He doesn't care for the gossip and smalltalk of other people's lives, but it's something to listen to just to keep his mind from wandering to somewhere altogether more unpleasant.

Until a snippet of one particular conversation reaches his ears.

"Winchester?"

That grabs Sam's attention. At first his instincts tell him to turn towards the source, but then he hears the next part of the sentence.

"You're serious? Carter has a Winchester as a client?"

Sam freezes. The coffee cup stays almost glued to his lips as he daren't move for fear of drawing attention.

"That's what I heard. Crowley's favorite getting in for some upgrades."

"I thought he was human again? His brother turned him back or something?"

"Yeah, that's what I heard, too. Good riddance to the douchebag."

"Well, whatever. But I'm telling you, Carter's got him in her clinic right now."

Sam realises his own heart has started pounding. He has to make a conscious effort to lower the coffee cup again, in case sitting with it like that should be even more conspicuous.

 _Demons._

"What the fuck is she doing? She treats demons, not hunters. Stupid bitch."

"I don't know about you, but I don't want to be dealing with a Winchester with a Carter upgrade."

"You think that's what he's doing there? What if she's…"

"Look, I don't fucking know, but I don't like it. Do you?"

"No. You think we should do something about it?"

"Her apartment's only up the street. I say we go and let her know what we think."

 _Shit._

Sam's muscles seem to have stopped working as he hears the shuffling of chairs from somewhere behind him, murmurs of agreement joining in with the first demon's suggestion. A handful of figures pass by his table and Sam immediately stares towards the window, praying that he won't be noticed. Or maybe he should be trying to do the exact opposite…

The thought has only occurred to him by the time he hears outside noise rush in through an open door, and then a soft thud as it swings shut. His mind kicks into overdrive.

They're going to Dean. Four demons are going to Dean while he's unconscious and vulnerable and in the middle of fucking _open heart surgery_ with his only protection being one powered-down angel and a standoffish demon doctor. Sam has to do something.

Exactly _what_ he doesn't know against four demons in broad daylight before they get as far as the apartment complex, but dammit he will do _something._

The coffee gets abandoned as a twenty dollar bill is flung down hastily beside it, and Sam gets to his feet and follows.


	4. IV

"Dish."

Carter doesn't exactly overflow with loquaciousness. It takes Cas a moment to realise she's asking for the cardboard dish on the table alongside the instruments. He passes it over, and she uses it to deposit a larger strip of tissue instead of wiping flecks on the surgical paper. If Cas was more prone to anxiety, he'd probably be struggling to watch this. If she takes too much and starts cutting out healthy tissue as well as dead, then it's only going to make Dean worse.

Cas suddenly frowns. Something's wrong.

"Do you have angel warding in here?"

He doesn't pick the best time to ask, but Carter doesn't appear to break concentration. Another chunk of cardiac tissue comes away. "You're the first angel I've met. Hardly seems like I'd need it."

"But you do have some kind of warding?"

"I've got invisible wards in Dee's original Enochian, plus some modifications. I assume there's a point to this question."

There is. Cas squints in concentration. "Somebody's trying to pray, but I can't hear."

"Yeah." She seems unconcerned. "I have no idea how that works."

"If Dean's lying there, the only person it could be is Sam."

"His brother's having major surgery. If he's the religious type, of course he's praying."

"No, there's something else. Something's wrong."

As if on cue, there comes the sound of an engine revving in the garage outside, followed by a distant crash. Only then does Carter glance up. A beat passes, then she ignores it and resumes working. Now Cas is concerned.

"I should check that out…"

He makes as if to leave, but Carter interrupts. "You wanted to be here. You leave now, don't come back."

He shoots her a glare. "I told you, something's wrong."

"And until it impedes my ability to carry out this surgery, I'm going to keep going. Help me or don't, but you're the one who promised you'd be useful."

She doesn't look at him, and Cas grits his teeth. There's definitely something going on, but he doesn't want to leave Dean alone with her.

Cas stays.

* * *

Ruby's knife is still in the trunk of the Impala. Sam doesn't have so much as a gun. His mind is in overdrive as he follows the band of demons down the street, trying to keep a brisk pace but hanging back enough not to be inconspicuous. He hardly manages it, colliding with more than a few people as he approaches the apartment block, but that's far from the first thing on his mind.

He sees the group of four turn into the entrance up ahead. They've gone through the main door, bypassing the garage entrance, and Sam wonders if taking that will get him there faster. He turns down the ramp and breaks into a sprint.

Carter's apartment is the far side of the compound. If he can make it there to warn them…still no good without weapons, he realises. He's already praying, but there's no guarantee Cas heard. _Dammit, Sam, you idiot. You have a phone._ The device comes swiftly from his pocket as he tries to dial and run at the same time, but all it does is ring. There's no answer.

Sam swears under his (now short) breath. He remembers Cas taking his coat off. If he's left the phone on vibrate…

Well, he's just gonna have to work with that. He takes a second ramp down to the lower level garage, apparently deserted, where the Impala is parked, and then glances from the car to the stairwell leading to the basement apartments. There's no sign of the demons emerging yet. He still has time.

Sam darts to the car, fumbling for the keys as he gets the trunk open and hurriedly searches for Ruby's knife. It should be here, somewhere underneath the ammo packs of rock salt and the holy oil. They had it just last week…

Of course. Sam curses again as he remembers. It's still in the glove compartment. He grabs a pistol instead before slamming the trunk and heading to open the driver's door, leaning across so that he can reach the glove compartment and the knife. Just as he does so, there's the pinging noise of an elevator arriving in the garage.

Sam glances up. He doesn't remember seeing the elevators before, but it seems there's one a few meters away, half concealed behind one of the pillars supporting the storey above. It's visible enough that he sees the doors slide open and the demons step out.

 _Shit._

Now he has to do something. There's a moment's hesitation as Sam grasps hold of the knife, keeping an eye on the demons through the window and then switching to the wing mirror as they begin to walk behind. They haven't seen him. Yet.

He has the gun. A thumb slowly pulls back on the hammer, and Sam prepares to dive out of the car again and take the shot. Then he has a better idea.

The driver's side door suddenly slams closed. Apparently, that's enough to get the demons' attention, the four of them halting as they realise they aren't alone. They don't react fast enough.

Tyres screech, the Impala's engine gives a roar, and the car suddenly speeds in reverse right towards where the four figures are standing. Three of them have the presence of mind to dive, but Sam's assault strikes home for one, and he hears the thud as a body slams into the back windshield. He slams the brakes just in time to prevent a collision with a Toyota Avensis parked nearby, and then the demon slides to the floor, leaving a smear of blood in its wake.

That's one down.

Sam's head whips back to the front, briefly assessing if it's worth slamming the car back into forward and going again, but one of the demons is already almost at the driver's door. Sam opens it and fires two rounds over the rim before there's chance for the demon to get too close.

The bullets strike, one in the shoulder, one square in the chest, but it does little to slow him down. The demon falters briefly, glances down at the smears of red seeping across his shirt, and smirks. "I take it you're the brother?"

Sam clenches his jaw, keeping the gun levelled as his other hand reaches for the knife on the seat behind him. It stays behind him as he exits the car. "Damn right. And I'm not about to let you in there."

"That so?" The demon gives him a mocking look before shooting a glance at the other two left standing. "You go. Just let me get things cleaned up here."

They follow the order, one of them leering in Sam's direction before they head for the stairwell, and Sam's attention turns back to the demon standing before him. He's a goliath of a man, a good couple inches taller and broader than the hunter himself. Sam really hopes this isn't going to come down to a fist fight when, with a flick of the demon's wrist, the gun is wrenched from his grasp. It lands on the floor several feet away and skids.

Sam grits his teeth as the demon takes another step closer. This isn't going to be pretty.

* * *

The crack of gunshots cut sharp through the stillness. Carter glances up briefly, just the slightest tilt of her head towards the wall in the direction of the garage. She doesn't look at Cas.

Now the angel _knows_ there's something wrong. His vessel's own heart is thumping faster, glancing from the wall down to Dean's face: unconscious, vulnerable… They can't afford for anything to go wrong. "I really should check that out."

Carter looks down again, her hands still buried in Dean's chest as she continues to work. "Alright. But whatever's happening out there, keep it out there. I have a job to do."

Cas nods. "Understood." He's not about to argue, but just as he's taken the couple of paces towards the door there comes the sound of a crashing from somewhere in the apartment. Heavy footsteps sound in the hallway and then the door swings open. Two figures stride in.

Eyes flash black as the two men survey the scene, Cas following their gaze as they take in the camera, the machines, the operating table, and Dean lying unconscious with Carter's hands in his open chest.

One of them, a burly man with dark hair and a short, wiry beard, shoots Cas a glare. "Angel." Then her turns to Carter. "And doctor. Any chance of an appointment?"

She looks up, a mocking eyebrow creeping up towards her hairline. "I'd greet you, but I really can't remember your name. Now, if you want something, go wait outside. In case it isn't obvious, I'm busy."

The demon smirks, taking a pace closer. Cas' eyes dart to the table where he's left his trenchcoat – and the angel blade – just far enough to be out of reach. "See, that's why I'm here," the demon continues. "Interesting clientele you keep these days. Upgrading a hunter? Can't say my boys are too happy about that."

Carter's gaze remains ice cold. "Do I need to explain the concept of free enterprise? He pays, just like the rest of you. You don't like it, I'm not making you use my service."

"Thing is," the demon narrows his eyes and tries to step closer, but Cas moves in front of his path. They lock eyes, both glaring, and then the demon stares over Cas' shoulder back to Carter. His lips twist in a snarl. "We'd really rather you just let the bastard die."

"Guess you're out of luck." Her expression doesn't falter. "Now you can either leave of your own accord, or something less pretty is about to happen to you."

The one still hovering by the door gives a laugh. "Yeah? Like what?"

Cas shoots him a glare, then his hand closes on the arm of the demon still stood next to him. "You try to touch Dean," he warns, voice a menacing growl. "I _will_ smite you."

He's met with a mocking look. "Last I heard, you weren't doing so hot, angel. You sure you got the juice?"

Cas' eyes narrow further. "You sure you want to find out?"

It doesn't break the tension, but an interruption comes in the form of a voice shouting from the hallway. "Cas!"

Sam sounds panicked, breathless, as he emerges in the doorway, knife clutched in his hand dripping with blood. He's panting as he takes in the scene, locking eyes with the demon nearest the door in a death glare, and then looking past to where Dean is lying on the table. A flicker of relief passes over his face. "What's happening?"

"We're just dealing with your brother, Sasquatch. We'll get to you next."

It's the demon nearest the door that answers, but Carter's expression suddenly turns to one that's positively amused. "Well, now you're outnumbered. So if you still wanna go…"

"Not quite." Another voice suddenly joins them. Sam wheels round, knife coming up as a figure emerges behind him: bloody and bruised, but on two feet again. It's the demon he'd almost run over. The two of them glare at each other as everybody seems to have reached a stalemate, waiting for someone else to make a move.

"Just great." Carter's tone has switched now to annoyance. "Now if you boys really want to start a fight, with me, in a room full of surgical tools and demon wards, be my guest. But it's not going to end well for you."

The first demon, still standing by Cas, chuckles darkly. He gives the angel a menacing glare then casually steps away. "Sure, you say that. But really, there's only one thing we came here to do, and the question is…" His eyes drift over to the bypass machine, still whirring as it pumps Dean's blood. "If we do get into a fight, and, say, something happens to the power, what happens to everybody's favorite hunter over there?"

The room suddenly goes very still. Six pairs of eyes all turn to the body on the operating table, half of them concerned, the other half calculating, and then the demon behind Sam suddenly steps forward into the room. It's not aggressive, but it's quick, and before Sam can even realise what's happening he sees the demon's hand come up towards the light switch by the door. He doesn't intervene in time before the basement room is plunged into absolute darkness.

All hell breaks loose.

Sam's hand goes quickly to hit the switch again, but before it lands he feels the demon grab hold of his wrist. Across the room, the only light to be seen is the blinking of monitor screens, and then there comes a sudden crash followed by a clattering as something sends the monitors hurtling to the floor. Sam lunges forward, stabbing at thin air with the knife, and then feels a kick to his knees. He grunts in pain and stumbles back. It's near impossible to tell what's going on, but then there's a sudden bright flash of white not far away – Cas smiting? – before everything goes dark again. There comes the sound of equipment flying, some grunts, blows landing, and then Sam's knife finally finds its target and a flash of red pierces the darkness. He hears the thud of a body hitting the floor and then scrambles to get the lights back on again, just as a high-pitched buzz hits his ears.

The lights flicker back on in time for Sam to see Carter clutching the power drill from earlier and drive it straight between the dark-haired demon's eyes. His mouth opens, apparently in a scream before smoke begins to seep out, but then it's cut short as red sparks in its eye sockets and the smoke disintegrates in a lick of flame. The body goes limp, and Carter gives it a kick as she pulls out the drill bit. A look of what almost seems like satisfaction spreads over her face.

The whole thing must have been over within a few seconds. Breathing heavily, Sam looks round to see the corpse of the third demon lying on the floor, eyes burnt out while Cas stands over it. The angel looks weakened from the smiting, chest heaving as he clutches at one of the tables for support. The monitor stand is on the floor, as is the equipment cart, plus several gas tanks and other instruments that were knocked over in the melee. Panic rises in Sam's chest as he looks to the bypass machine to check that it's working, then realises the power cord has been pulled free from the wall. "Dean!" He rushes over to his brother, only half aware of Carter in the corner of his vision until she gives the drill a whir again. It's not plugged into anything.

"Relax, l'Oreal," she says casually. "Batteries. That thing's got a four hour backup capacitor on it. We're good." She discards the tool on a table along with her still bloodied gloves, not bothering to replace them as she hurries to check on Dean. She gives a cursory glance over the tubes anchored inside his chest, then tests it with her fingers, looking to one of the monitor screens still facing upwards where it landed. By some miracle, with all the equipment that went flying, Dean seems unhurt. "No leaks," Carter announces, then checks his lungs. "Breathing still under control. He's fine."

Sam can't describe the relief he feels at those words. Satisfied, Carter turns away from Dean again and starts trying to get the room back into some semblance of order, putting the bypass machine back on mains and picking up the monitors. "You both just gonna stand there, or you gonna actually help at some point?" It takes Sam a moment to really process what's happening, suddenly realising for the first time that he's staring down at his brother's unconscious body while Dean's chest is laid open and his heart is barely unrecognisable as an organ anymore. He feels a wave of nausea, some uncomfortable feeling in the pit of his stomach, then buries it down. He needs to hold it together.

While Sam begins gathering up the equipment, Cas is still leaning unsteadily against one of the tables, breathing shakily. "How did…" He has to pause to gulp down air, glancing from the corpse with a hole in its head to Carter. "How did you kill it? Without a weapon? Or a spell?"

"Warding," Carter answers bluntly as she tries to reset the monitors. "I don't let them smoke out when they're in surgery, otherwise I'm pretty sure half of them would bail. And if they do try anything…well, you get the right wards and hit them in the right spot, that sends the whole thing up in flames. Usually between the eyes does the trick."

It perturbs Sam when he sees the monitor displaying a flatline, yet with the bypass in place, he knows it's supposed to. Carter turns away from it and raises an eyebrow at Cas. "Are you actually gonna be useful from now on, or is that your load blown?"

It's rude, and Cas can't help the scowl that creeps across his face. "No, I'm good. It's just…" He straightens up and tries to help with retrieving the equipment. "My grace. Smiting can be taxing. I'll be alright soon enough."

"Hmm." Carter raises a dubious eyebrow, but makes no further comment. "Alright. Now you can both help me. This will all need re-sterilising now."

She sounds pissed, but to Sam's ears, not exactly overflowing with concern for Dean's wellbeing. A handful of surgical tools get snatched from the floor before Carter dumps them on a trolley, which she begins to wheel back over to the table. She passes by the corpse of a demon and gives it a kick to make way for the equipment cart, then strides over to a can of gas that's rolled across the floor. She takes one look at the dents in the side then murmurs, "Shit."

The word is disconcertingly ominous. Sam's mouth goes dry. "What?"

"That was the last of the anaesthetic."


	5. V

It takes a few moments for that to sink in. The soft hiss of gas seeping from the punctured tank is suddenly deafening. Sam blinks, swallows, then says, "What?"

Carter just scowls as she rights the damaged tank and casts a glance at the ones still hooked up to the vaporizer, paying him no attention. There are definite traces of worry in the hard lines of her expression.

Sam feels like his world has stopped turning. He tries again. "He's not going to wake up, right?"

Carter still doesn't glance back at him as she checks the remaining connections. "There's one tank of nitrous oxide left, but that's not going to be enough to keep him under. I think we have half…" She reaches for a tank that's lying on its side with the tube still screwed to its nozzle, but as she rolls it back towards her it reveals the connection's already come loose. Carter picks it up and purses her lips as she feels the weight. "Nope. Just the nitrous oxide."

"But you have more?" It's Cas who interjects this time, and Sam can hear the faint panic in the angel's usually calm voice.

Trying to salvage what she can, Carter goes for the leaking tank and presses her hands over the dents, but gives up as it becomes apparent the weight of falling equipment has punctured it in too many places. "Usually, I only need the nitrous oxide to deal with demons. I bought one tank extra of everything else just for this. And now…well, you can see where we're at."

 _Shit shit shit no no no_ keeps running round Sam's head, if his panic is managing to form any words at all. He glances down at his brother's face again, and then can't help it as his gaze is drawn to the bloody mess of Dean's open chest. He can't wake up like that. He can't. "What now? How long do we have?"

Carter bites her lip, and Sam thinks it's the most concern she's shown thus far. "In theory, he should have at least four hours before waking up."

"In theory?"

She lets out a heavy sigh. "Last time he came here, he was showing signs of a hyperactive metabolism. If that's the case… well, I don't know how long. Would you say he's been eating more than usual? Or been more restless?"

Sam's mind races. He wants to be able to tell her _no, he's been fine, no different from usual,_ but realises he can't. "He, uh… yes. He has."

"Alright." She clenches her jaw as she gets back to the equipment they've retrieved and begins the process of re-sterilizing everything. "I best get back to it then. How would one of you feel about robbing a hospital?"

Cas answers before Sam has chance. "I'll do it."

Carter peers up from the scalpel in her hands, one eyebrow raised. "To be honest, I was aiming that more at him." She jerks her head towards Sam. "You don't exactly look up to anything right now."

A look of determination settles on Cas' face as he straightens up. "No. It would be better with me. I can get in undetected, obtain the anaesthetic without anyone even knowing I was there."

That draws dubious looks from both Carter and Sam. "Cas, you're sure?" Sam begins to ask, but Carter gives a shake of her head.

"Well, I don't have time to question you. If you're gonna go, go now. You know where the hospital is?"

"Yes." The answer almost seems irritable as Cas discards the apron and pulls back on his trenchcoat, jaw set in a solemn line. There's a moment as Sam wonders if he should intervene, offer to go instead, but if Cas is right about going undetected then it would be better for him to leave and Sam stays with Dean. Of course, it's all dependent on him recovering power soon. _Very_ soon.

"You know what you're getting?" Carter asks abruptly, to be met with an equally abrupt answer.

" _Yes._ " His look says it all. The centuries worth of knowledge of human medicine has its use.

A brief look passes between Sam and Cas as the angel heads for the door, each of them seeing their own fear reflected in the other's face. If Dean doesn't make it…

Sam isn't even going to contemplate that thought. The next thing he hears is a somewhat snarky, "I suggest you drive," from Carter as Cas heads off down the corridor. They hear the apartment door close, and then Carter looks back down at the tray of instruments without a glance at Sam.

"Pick that up for me, would you?" She nods sharply towards the camera and tripod now lying askew on the floor, apparently unconcerned about the unconscious body on the operating table in front of her.

Sam stays by his brother's side. "What about Dean?"

"He'll be fine, as long as you stop questioning." She scowls in irritation.

Not that it's any assurance, but Sam casts a final lingering glance at Dean then does as he's asked. It still makes something churn uncomfortably in his stomach that she's recording this. Even if it's supposedly for 'medical research'…

Nausea sweeps over him briefly as he tries to get the camera focused on Dean's chest again, exposed tissues glistening red, and then he gets a grip on himself. "Alright, now what?"

He asks it just as Carter picks up a pair of forceps in her spare hand and leans back over Dean's chest again. Sam can't help the shock as she peels back a flap of cardiac tissue and then sets the scalpel scratching away at a ridge of white underneath. "Fuck it, I'm not gonna have time to do everything. You can get the clamps and needles sterilised." She swears under her breath as a gush of blood suddenly wells up from _somewhere_ and seeps out over the blade, obscuring whatever she was working on. "Actually, no. Think we've got leaks. Get the suction. I'll take off the scar tissue closest to his atrium then close him up. It's not ideal, but he'll live with it."

Sam hates his own uncertainty as he picks up the nozzle and realises he doesn't know what the fuck he's doing. His eyes land on Dean's face, the tube shoved down his throat, and then snap back to the gaping red maw of his chest. Panic grips him.

His hands tremble. Everything feels unreal as his mind struggles to process, like his fingers don't even belong to him as they lower into his brother's chest cavity and try to draw the redness away. Instead, it clings to him. Dean's blood. The blood that ought to be pumping through his brother's heart is right now spilling out into his hands. Literally. And he doesn't know what to do as it just keeps coming and he's supposed to be sucking it away but where is it meant to go if it's not in Dean's body and what if…?

There's an unexpected relief as he suddenly feels a firm hand close over his, jerking him back to reality. Carter snatches the nozzle off him with a scowl. "I was better off with the angel." She sucks the blood away while keeping a firm hold of Dean's heart with the forceps, then, with surprising dexterity, keeps the scalpel gripped in the same hand as the suction tube as she switches back to cutting. She's fast and efficient, and if Sam weren't so otherwise distracted, he'd find it impressive.

Guilt at his own uselessness pangs somewhere below Sam's sternum, yet somehow it's easier to breathe. He watches silently for several moments, throat feeling tight before he even thinks to try to speak, but Carter beats him to it with a shake of her head. "Look, if you like, you can start sterilizing the rest of the instruments. Or try getting these bodies out of here." She punctuates that by nudging the smote demon with her toe, eyes never leaving Dean's chest. "As long as I can work."

Sam swallows, but he's grateful that for once, she didn't snap. That sounds useful. "Alright…" He tentatively picks up and alcohol wipe and a suture needle as he goes to hover a safe distance away. He's deliberately ignoring the bodies for now. He can't leave Dean on his own. "What, uh…what do you need first?"

"Look, just…" She clenches her jaw in irritation, then softens slightly. "The clamps. The internal defibrillator. Whatever's left on the table, the floor… Just do what you can, alright?"

That's direction enough. Sam works diligently for the next several minutes, trying not to be any more of a distraction, but it's hard to keep his gaze away from Dean. There's one horrible, persistent thought lingering at the back of his mind. In the end, he can't keep it buried down. "What if he wakes up?"

"I'm going fast." The answer isn't dismissive. Instead, it's urgent. Sam thinks that's worse.

It can't be that long after that Sam starts to wonder how long Cas has been gone or when he'll be back. He realises he's lost track of time completely. Everything seems to be happening all at once, yet taking far too long. Dean needs that anaesthetic. Every time Sam's eyes land on his brother's face again, practically as frequently as he draws breath, he imagines Dean's eyelids struggling to open. Face distorted in pain, choking on the ventilation tube as he feels the agony of his chest being split in two, his heart in shreds…

No. Sam's not going to picture that.

"Alright. That'll do." It takes him by surprise when, at length, he hears Carter's voice again. "He's gonna have reduced stroke volume, but it's the best I've got against the clock. You got some sutures for me? I'm gonna get his heart closed up."

That's good news. Or at least, Sam knows he ought to be taking it that way. The anxiety gnawing away in his stomach doesn't get the message. "Yeah, here." He can't be more eager to help, pushing the tray of instruments closer to her. She barely gives him any acknowledgement as she picks up the needle and thread.

"Go scrub your hands and put some gloves on. I might need some help."

Sam doesn't question it. Now he thinks he gets why she told him not to.

He's fast but thorough as he gets scrubbed down, soaping up to the elbows before drying off and snapping on a pair of gloves from the box by the sink. At last, he's glad he'll be doing something directly useful, whatever it is. Carter has already made the first couple of stitches by the time he gets back to her. "What do…?"

She doesn't give him chance to finish the question. "I need you to hold his heart."

Sam swallows. "What?"

"Just put your hand underneath and keep it squeezed shut. I need to get a tight seal."

"You mean…" Sam has to remind himself to breathe as he stares down at Dean's heart. He's not squeamish, but the reality of this is hard to process. "Keep the edges closed together?"

"Yeah, they're not gonna match perfectly. I may need to make a few corrections."

Sam nods solemnly and then allows his hand to creep into Dean's chest cavity. He's tentative at first, but then forces himself to pull it together as he slips his hand beneath Dean's heart and begins to squeeze. The yielding softness of the muscle surprises him, but it's the surprising coldness of it that triggers a wave of dread.

"Other hand too." Carter barks the order bluntly. "Pinch it if you have to. I need this as tight as possible."

Sam's careful to avoid the tubes attaching to the bypass as he does as he's asked. He steels himself to watch Carter push the needle back into the organ again, but despite his grimace, he finds it's better than staring at Dean's heart in pieces.

Carter works as quickly as she can. Sam can tell, but even so it doesn't seem to be moving fast enough. It's slow progress watching her stitch Dean's heart back together, the pieces mismatched, not quite lining up. Sam can't decide where to look, his hawk like focus on Dean's heart broken only by the intermittent need to glance at Dean's face; remind himself that this is really his brother lying there. Still alive. Still fighting.

Dean's heart is about half pieced back together again when a glance at his brother's face shows Sam exactly what he doesn't want to see. His own heart stops. "Carter!"

Sam barely hears himself, but there must have been some extreme urgency in his tone that for once, she actually looks up at him.

"What?"

"His eyelids fluttered."

Just briefly, Sam thinks he sees a look of anxiety pass over her face as she glances at Dean. "They're taped shut."

"I know."

A beat passes. They both lock eyes, and then Carter mutters, "Shit."


	6. VI

Immediately, she drops the scalpel and forceps, tossing them still-bloody back onto the table as her hands fly to Dean's face. Red smears across his cheek, going ignored. "Dean?" No response. _That's good, right…?_

It doesn't reassure either of them. Carter tears off the tape over Dean's right eye, thumb pulling back his eyelid as she watches for a reaction. Sam hears her sharp intake of breath as Dean's pupil constricts, and then, worse, moves.

It's just a shudder, involuntary maybe, but Sam feels the pit of his stomach drop out. He's not even paying attention as Carter steps away to do God knows what else, instead raising his own hand to cup Dean's cheek, the other doing all he can think of and searching for his brother's hand beneath the paper sheets. "Dean!"

No reaction. Please let there be no reaction. _Unless, was that…?_

He gets cut short wondering if he imagined movement or not as his other hand finds Dean's wrist. Something unexpected meets his fingers, and instinctively, he glances down, confusion adding to the fear written on his face. Leather restraints are fastened tight around Dean's arms. _Why did she…?_

The question gets pushed aside as Sam looks up again to see Carter fiddling with the bypass machine. Instead, the most pressing issue right now is, "What are you doing?"

She doesn't look back. "I'm dropping his circulation rate as low as I can get it without causing brain damage. Shouldn't be enough blood flow to keep him conscious…in theory."

That earns her a grave look. "That's the second time today you've said something will work 'in theory'."

Sam almost wishes he hadn't pointed it out. She glances back at him, bottom lip caught between her teeth, but the look is the exact opposite of reassuring. It only adds to his anxiousness as he turns his focus to the machine, hearing the whir of its mechanisms slowing as he prays that this will work. _Cas, hurry up,_ he thinks silently, his lungs leaden as he holds his breath.

For several seconds, he thinks that maybe that strategy worked. No more movement disturbs Dean's face: no twitching of muscles, no flutter of eyes beneath their lids… Then ice clamps around Sam's heart as he feels the unmistakable twitch of Dean's fingers. "Dean!" His hands grip his brother's tighter.

Carter swears again. "Fuck."

Sam barely has time to see if his brother's eyes crack open before she's shoving him out of the way. Her hand returns to the side of Dean's face, palm hovering by his right temple as she raises her other fist to the opposite side of his head. It clicks with Sam just as he thinks he sees the flutter of Dean's eyelashes drawing upwards, and then Carter's hand collides with his skull with a smack. Dean's head jerks stiffly. It's not enough to dislodge the tube in his throat, thankfully, as Carter damps the movement with her left hand and then eases his head back down onto the table. With a wave of relief, Sam sees Dean's eyes have gone still. "Failing that, I guess blunt force trauma works."

Sam draws a deep, calming breath as he realises his own hands are shaking. He knows it's not going to last. "Now what?"

Carter bites her lip again, grey eyes flitting down towards Dean's chest. For a moment, she appears uncertain if he might just continue to wake up anyway. Then she decides to pick up the scalpel again and get on with it. "You best hope your angel friend gets back here soon."

She gets back to work, paying him no further attention until Sam realises he's still gripping onto Dean's (limp, disconcertingly cold) hand. He tugs at the bonds. "You mind explaining this?"

Carter's eyes flicker up briefly. "His idea. Not mine."

A sick feeling starts to creep its way up from Sam's stomach. He doesn't have chance to press if further before they hear the sound of the front door opening and movement in the hallway. Both of them turn in time to see Cas walk through the doorway, still looking pale, but with two cylindrical tanks tucked beneath his arms. Relief washes over Sam while Carter just glares.

"Well, your timing is fucking awful."

That's a more panic-inducing statement than necessary, and Cas' eyes slightly widen. "What happened?"

She doesn't answer before she's already striding over to take the tanks off of him, leaving Sam to try to fill him in without succumbing to his own sense of dread. "It's okay." His voice is strangled, not exactly convincing. "There was a moment we thought he was waking up, but he didn't. We got back him under, and you're here. So we're good." He sounds like he's trying to reassure himself.

Anxiety passes briefly over Cas' face, eyes drawn to Dean, and then he turns to watch Carter adjust the vaporizer. "Halothane and isoflurane. Will that do?"

"Yeah, that'll do." She sounds stressed, though for Sam, there's only relief that finally his brother will be properly anaesthetised again. Maybe now he can actually believe it: Dean's gonna pull through and everything will be okay.

Carter adjusts the bypass machine again as she checks the new mix of gases, and then gets back to work. Cas hovers nearby, prepared to assist, but there's little for either of them to do as Carter works in stubborn silence. It isn't long before she irritably snaps at them to try and get more cleaning up done.

They do, managing to restore some semblance of order to the room while she works. The bodies get shifted to the hallway, Cas and Sam exchanging grim glances, but they barely talk. The angel still looks exhausted, his grace near spent. It makes anxiety bubble up even worse in Sam's stomach. If something were to go wrong now, if Dean needed emergency angel healing to pull him through… well, it's not coming from Cas.

They wait it out, each minute dragging on far too long, until Carter finally straightens up from Dean's chest and sets her instruments aside. "Alright, that'll do." She reaches back into Dean's chest cavity briefly to remove the clamp from his aorta. "Let's get him off the bypass."

Immediately, Sam snaps to attention. He's prepared to do whatever she asks next, but Cas beats him to it without instruction as he hands her a pre-prepped syringe from one of the tables. It's long and fine, filled with a clear fluid Sam can't identify. "Restore his heartbeat then remove the tubes?" Cas clarifies.

"That's the plan." She accepts the needle then lowers it towards Dean's heart, eyebrows drawing together in concentration. "Just need to get it moving again then I'll shock it back to rhythm." She tests a couple of spots with the point, working around the gnarled line of stitches she's left behind, and then sinks the end into Dean's right ventricle. She depresses the plunger.

Sam holds his breath and waits.

For several seconds, nothing happens. Sam's fists clench and unclench, his own heart thumping so loud it's like it's calling to Dean's to join it, but the mass of muscle in his brother's chest remains still. Dread is just beginning to overwhelm him as he realises both Cas and Carter are staring at the monitor instead. He shifts his gaze, drawing another breath of hope, and could almost laugh with relief as he sees the flat line of green begin to ripple. He looks down at Dean's gaping chest again. The red, glistening lump that holds his brother's life force gives a quiver.

"Alright. Let's get it back in sinus rhythm," Carter says.

Already, Sam feels the tight knot of anxiety in his stomach begin to ease. He can't relax just yet, but it's not so hard to find himself as a bystander this time as Cas hands the defibrillator paddles over to Carter, who slides them either side of Dean's heart and then gives the organ in between a squeeze. "Charging." And just like that, Sam once again forgets how to breathe. "Shocking."

There's no loud zap. No sudden jolt. Instead, there's just a quiet thunk as the mechanisms in the machine discharge, and Dean's heart clenches. Then it resumes its feeble quivering.

With no change in her expression, Carter recharges and prepares to try again.

Sam's mouth has gone dry. It feels like the room around him is shrinking, everything growing small and tight until there's barely any room to breathe. There's only space for him and Dean and the trembling heart he's silently begging to beat.

The next shock comes. A beat passes, Sam hoping maybe the response is just delayed, but then Dean's heart just gives a feeble shiver again. He looks to Carter's face, hoping to see some kind of assurance, but it surprises him to catch the subtle glance she shoots in his direction. She looks worried. "Don't worry. It usually takes more than a couple of tries." It would sound more convincing were her jaw not clenched so tight.

She goes again, and again Sam watches as his brother's heart tries and fails to spring back to life. This time he looks to Cas, only to see the angel looking on with as much helplessness and fear as Sam himself. There's nothing he can do.

Carter tries one more time, and then swears angrily as Dean's heart fails to even give a tremor in the aftermath. "Dammit, Dean."

It's the most concern Sam thinks she's shown as she pulls out the paddles and thrusts her hand back into Dean's chest, closing a fist around his heart and rhythmically squeezing. Then, the full weight of Sam's panic spills forth. "What's happening?" It comes out choked. He doesn't need to ask. He knows already, despite his desperate hope that maybe one of them will lie to him, tell him things aren't what they seem, but he knows what this means.

Neither Cas nor Carter speak.

It feels like Sam's been watching the nightmare play out for an eternity before Cas at last steps forward, grim determination on his face as a hand extends to rest on Dean's forehead. He scrunches his eyes shut, and if Sam just prays hard enough maybe that will give the angel back what he needs and Dean will be alright…

The hope is shattered moments later as Cas draws back, visibly drained from the effort, and Carter snaps as she snatches up the paddles again. "You're not helping." Dean's heart has gone altogether still now, but still Sam's silently pleading with the universe to let him live as Carter thrusts the paddles around the organ one last time. She charges, shocks…nothing.

Sam's world has stopped turning.

He doesn't know how many times Carter tries again. Maybe she keeps going for a long while, refusing to give up. Maybe she abandons hope after just one more round. Either way, the next thing Sam's aware of is that she's flung down the paddles once again and is striding out of the room.

It takes a moment to register. Then, "Hey!" He ignores Cas, striding after her as sudden anger bubbles up to replace the terror coursing through his veins. She's not about to leave his brother lying there like that, not with his chest all open and bloody when she hasn't even finished. She has a job to do. "Hey!"

Carter doesn't look at him. Instead, she continues to stride towards the kitchen, spattering the walls with flecks of blood as she snaps off her gloves and flings them with excessive force to the floor. Sam follows, barely taking it in as she opens cupboards and starts taking stuff out.

For just the briefest moment, there's that treacherous glimmer of hope again, telling him that maybe she has some miracle cure hidden away and she's getting it out and will go inject it into Dean and he'll be just fine. Then he realises she's holding a bottle of whisky. "What the fuck are you doing?" There's pure fury in his voice.

"Getting a drink." Still she won't even do the courtesy of looking him in the eye, and his blood boils.

"Like fuck you are. My brother's still lying on your operating table waiting for you to finish what you started. Get back in there and fix him."

She doesn't respond. Something wrenches in Sam's gut as the reality of what's happening finally starts to sink in. He wants to scream at her. Shake her. Punch her. Anything to get her to cut this crap and go and do her fucking job. Instead, he finds he can't move. Can barely speak. All he does is watch as she pours amber liquid into a tumbler and raises it to her lips, knocking it back in one long, steady gulp. Only then does she turn to face him. There's an unexpected glassiness to her eyes, and it hits him like a punch in the gut.

"There's no point, Sam. He's dead."

 _TBC..._

 **A/N: Well, that was certainly a downer ending, wasn't it? But don't worry. Rest assured, a sequel is coming. I'm not done with Dean just yet.**


End file.
